ADT Tune Measurement F. Dubouchet, W. Hofle, D. Valuch Acknowledgement: R. Calaga, F. Roncarolo, E....
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Transcript of ADT Tune Measurement F. Dubouchet, W. Hofle, D. Valuch Acknowledgement: R. Calaga, F. Roncarolo, E....
W. Hofle @LBOC 21.08.2012
ADT Tune Measurement
F. Dubouchet, W. Hofle, D. Valuch
Acknowledgement: R. Calaga, F. Roncarolo, E. Bravin, shift crews
New developments and tests on August 1st and 12th 2012
W. Hofle @LBOC 21.08.2012
ADT Tune Measurement
Reminder (Chamonix):
Plan:implement gain modulation to selectively reduce ADT gain for witness batch (Chamonix: 12 bunches Now: 6 bunches) done, but no improvement for BBQ
situation: BBQ gating difficult, BI working on it, tests upcoming long term ADT plan: tune from residual ADT signal massive data treatment, limitations of VME technology not operational before LS1 as new hardware required
Plan B: kick beam (witness batch) selectively by ADT and record free oscillation make an operational tool by combining with already commissioned batch by batch gain modulation
use new 16384 word long dedicated study buffer on FPGA of ADT DSPU VME cardmethod gives also the ADT damping time along the cycle monitoring of performance
W. Hofle @LBOC 21.08.2012
Timeline of tests on August 1st, 2012
1 3 542
1: 6 turns kick (16x)2: 3 turns kick (21x)3: 5 turns kick (28x)4: 5 turns kick (7x)5: 5 turns kick (500x)6: 5 turns kick (52x)
total: 624x
5: frequency trim6: tune trim
6
6 bunches, nominal intensity 1.5x1011/bunch beam measurements with 1 beam only, V-plane; both beams injected (6 bunches)using existing firmware / infrastructure (abort gap cleaning), kicking at 0.31 in tune
450 GeV, but damper gain adjusted to model situation at flat-top (damping time of 100 turns)
W. Hofle @LBOC 21.08.2012
Lifetime during excitation of 6 bunches
start of continuous burst excitation [1 burst every 2.34 s]
BLM lifetime drops from 200 hours to below 100 hours
W. Hofle @LBOC 21.08.2012
Lifetime cont.
end of burst mode of 500 excitations
BLM lifetime recovers after stop of excitation
excitationsre-started
W. Hofle @LBOC 21.08.2012
Blow-up of the 6 bunches as a result of kicks
initial test (manual triggers) then500 bursts (each 5 turns)from 13:45 to 14:05 (19.5 min)2.34 seconds per burst
td = 100 turnsmax amplitude 100 mm at Q7V.B1 of damper
1st period: 45 minutes, 3.3 nm / min0.149 mm for 72 excitations + normal blow-up
2nd period: 19.5 minutes, 43.3 nm /min43.3 nm /min 0.844 mm in 19.5 min0.844 mm for 500 excitations + normal blow-up
deduce blow-up w/o excitation (assumed to be a constant rate per unit of time):0.65 nm/min, i.e. 29.25 nm during 1st period
12.68 nm during 2nd period
blow-up per trigger (excitation)1st period: 72 triggers: 1.66 nm per excitation2nd period: 500 triggers: 1.66 nm per excitation
500+5272
excitation bursts (approx)
F. Roncarolo, E. Bravin
W. Hofle @LBOC 21.08.2012
Tune trim (data set ‘6’)
1e-3 up and down
tune
time
(hou
rs, d
ecim
al)
W. Hofle @LBOC 21.08.2012
RF frequency trim
VCXO word
40 Hz up, i.e. from -20 Hz to +20 Hzwith respect to central frequency of 400.788’837 MHz
FGC frequency(logging on change)
time [1 min / tick]
14:03:37
W. Hofle @LBOC 21.08.2012
RF frequency trim (data set ‘5’)
40 Hz up, i.e. from -20 Hz to +20 Hzwith respect to central frequency 400.788’837 MHz
DQ = -4.9e-4 DQ = - 4.9e-4 Dp/p = - 3.2e-4 Q’ = + 1.5
single bunch (!), single pick-up Q7.VB1, 2730 turns, 500 times kickedtune
time
(dec
imal
)
14:03:3x
W. Hofle @LBOC 21.08.2012
2nd peak at -20 Hz also visible for FFTs of individual bunchesReal modulation of beam tune or artifact ?
Data Set 5, 500 measurements, FFT average over 6 bunches
W. Hofle @LBOC 21.08.2012
Example of a single bunch, single measurement FFT (V.B1)
50 Hz
20 Hz
2730 turns resolution too limited to clearly resolve if there is a systematic peak at 20 Hz in the low frequency range
W. Hofle @LBOC 21.08.2012
3.5 TeV, 8 MV fs=22.9 Hz
compatible with Qs and 2Qs, fs=22.9 Hz
50 Hz
Clean spectrum between 50 Hz and tune
tune
2010 data17 May 2012damper offlow bunch intensityFFT of 4 bunches(65536 turns)
10 20 100 1000 1 frequency in Hz
FFT
(B2.
V Q
7L)
4.5 Hz
broad noise @20 Hz
2010 data
W. Hofle @LBOC 21.08.2012
Data Set 5, 500 measurements x 6 bunches
W. Hofle @LBOC 21.08.2012
Data Set 5, 500 measurements x 6 bunches
W. Hofle @LBOC 21.08.2012
average: 1.8x10-3 in tune 20.2 Hz
cut:only measurementsare displayed in which upper and lower tune peaks are the highest peaks for at least one bunch
W. Hofle @LBOC 21.08.2012
2nd test (12th August 2012)dedicated firmware deployed (Daniel), new dedicated fesa classes (Frederic) for excitation similar to AGC, but “skimmed down” excitation scales automatically with normalised damper gain
dedicated parameters and resources:
window (gating on part of the beam)DDS to generate excitation with programmable excitation frequency number of kicks (in turns)dedicated memory on FPGA (16384 bunch x turns)
max 2730 turns for each of the 6 bunches kicked
beam test (12th August 2012)
injected 2x6 bunches per beam with standard, i.e. minimal possible spacingsymmetric pattern with collisions in IP1 and IP5 only (bucket 1 and 651)use first 6 as witness bunches, kicked by ADT, 4 planes x beamskicked every beam and plane once per 4 seconds
(rotating kicks every second between beam and plane)4 turns kicked at 0.28 (H) and 0.31 (V), amplitude 0.8 of max
real life
no changes to operationalParameters and functions
W. Hofle @LBOC 21.08.2012
Damping times
Fill 2956
collisionsflat top and squeeze
Beam modes:19:33 prep4ramp19:37 ramp19:50 F-top20:15 squeeze20:39 adjust21:26 dump
injection
Daniel’s tool
ramp
W. Hofle @LBOC 21.08.2012
Horizontal Beam 1
Fill 2956
collisionswith S / pmodes
tune changeat start of squeeze
ramp
setting-upthen refill
Beam modes:19:33 prep4ramp19:37 ramp19:50 F-top20:15 squeeze20:39 adjust21:26 dump
flat bottomhigh ADT gainneed lowerADT gain for the first 6
FFTs from 6 bunchesaveraged
W. Hofle @LBOC 21.08.2012
Horizontal Beam 2
Fill 2956
collisions
spurious at 0.3068n x frev +/- 3450 Hzmesses up spectrum need to kick harder
ramp:tune took a dive due to tune FB locking on wrong lineswitched off and corrected at FT
flat bottomhigh ADT gainneed lowerADT gain for the first 6
setting-upthen refill
Beam modes:19:33 prep4ramp19:37 ramp19:50 F-top20:15 squeeze20:39 adjust21:26 dump
spurious
FFTs from 6 bunchesaveraged
W. Hofle @LBOC 21.08.2012
Vertical beam 1
Fill 2956
collisions
flat top spurious messes up spectrum need to kick harder
Beam modes:19:33 prep4ramp19:37 ramp19:50 F-top20:15 squeeze20:39 adjust21:26 dump
FFTs from 6 bunchesaveraged
W. Hofle @LBOC 21.08.2012
Vertical Beam 2
Fill 2956
collisions
flat top withspurious messes up spectrum need to kick harder
Beam modes:19:33 prep4ramp19:37 ramp19:50 F-top20:15 squeeze20:39 adjust21:26 dump
FFTs from 6 bunchesaveraged
W. Hofle @LBOC 21.08.2012
Individual bunches
20 Hz line moves with beam tune !
W. Hofle @LBOC 21.08.2012
Individual bunches
20 Hz line moves with beam tune !
W. Hofle @LBOC 21.08.2012
F. Roncarolo, E. Bravin
Emittance blow-up
W. Hofle @LBOC 21.08.2012
F. Roncarolo, E. Bravin
Emittance blow-up
W. Hofle @LBOC 21.08.2012
F. Roncarolo, E. Bravin
Emittance blow-up
W. Hofle @LBOC 21.08.2012
F. Roncarolo, E. Bravin
Emittance blow-up
W. Hofle @LBOC 21.08.2012
Towards making an operational tool – next steps
•implement control of parameters in sequencer, plus start / stop functionality (t.b.d.)•implement FFTs in front-end (0.45 ms/FFT, 12 FFT 5.4 ms (6 bunches, 2 PU) •average FFTs in front-end publish averaged FFT and tune (peak), fitting (?)
•make operational with 1374 bunches once sequencer work completed, andacquisition working
•explore parameter space to get desired resolution understand and decide how to deal with the spurious 20 Hz line next to the tune (!)
needs: gain modulation programmed to tailor damping time of the 6 buncheskicking harder at flat top when spurious lines perturb (kicking to larger amplitudes by increasing the number of turns kicked or by
increasing normalised gain + additional gain modulation to maintain same gain for main beam)
suggestion: use more turns of excitation when amplitude is insufficient and flat-bottom: gain modulation 16/128 for the 6, 127/128 for restramp / flat-top / squeeze: gain modulation 64/128 for the 6, 127/128 for rest